Re: PS Preview
Re: PS Preview
- Subject: Re: PS Preview
- From: Kevin Muldoon <email@hidden>
- Date: Sun, 28 Jan 2007 20:37:39 -0500
By merely assigning which profile?
By merely assigning a CMYK image any profile that is not the profile which created it we introduce conversion errors because we lose the ICC managed 'realness' of those numbers. Here is proof of concept.
1) Create a new file in Photoshop and assign the profile of an in-house, non-color managed output device such as a Kodak XP Approval. 2) Create four separate 100% patches of CMYK in the digital file. 3) Print a proof and place in a color booth next to the monitor.
As counter intiutive as it may be, we easily see that the CMYK patches on the proof do not match the patches on monitor even though we assigned the correct profile to the image. Measuring the proof with a spectro will yield even more interesting results, but let me move on to the point.
This test shows that we should think of ICC as a separation technology. It creates the separation that is appropriate for the specified output device/media but that doesn't mean ICC has a 100% accurate idea of what those CMYK numbers mean! The only thing ICC knows (so long as it has the proper profile) is what combination of CMYK numbers it would have chosen to create a color representation that best matches color X that was in a well behaved color space.
ICC was designed to go device independent forward but not CMYK backwards.
I understand people 'softproof' CMYK backwards all the time and they are mostly happy with the results. Those people who are becoming not happy could see an improvement by separating appropriately to the intended output device/media combination if possible!
Thanks!
-- Kevin Muldoon
On Jan 28, 2007, at 6:13 PM, Roger Breton wrote: However, prepress users will often view a CMYK file in PS Preview to see how un-transformed CMYK numbers will behave on his proofer and I believe this is an inappropriate use of the technology.
By merely assigning which profile?
I have learned not to trust monitor display of files separated into one color space and assigned another color space.
It seems to me you don't trust Photoshop's softproofing capabilities, more than the very idea of softproofing. Am I reading you correctly?
If the prepress user has the freedom to color correct then the prepress user has freedom to re-separate into the color space of his proofer and save themselves the time and expense of retouching.
True, with all the consequences previously discussed here. That's a professional judgement call and, to some extent, a matter of prepress policy. It has pros and cons.
Kevin Muldoon
Kevin Muldoon TrueBlueDot Fine Art Reproductions 156 Maple Street New Haven, CT 06511 p : 617.460.0023
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